The present invention relates to an improved threeplate slide valve closure for use in liquid melt containers such as steel ladles.
This type of slide valve closure is known, for example as shown in German Pat. No. 1,783,172, and includes spaced upper and lower stationary plates with a slide plate movable positioned therebetween. The three plates have therethrough flow-through openings which align with each other when the slide plate is in an open position, such that a liquid melt may be dispensed from a liquid melt container through the flow-through openings in the three plates.
Such conventional arrangements provide that the flow-through openings in the three plates are of identical cross-sections, with the exception of a slightly conically narrowed shape of the flow-through opening in the lower stationary plate. Such slide valve closure suffers from the inherent disadvantage that when the slide plate is moved to the closed position thereof, since such movement is relatively rapid, some of the liquid melt will be maintained within the volume of the opening of the slide plate and will be trapped therein. Such trapped melt will solidify and will thereafter interfere with the further use of the slide valve closure. In the worst case, such solidified portion will completely block the flow-through opening in the slide plate.